DESCRIPTION: This video is a mix of live action and animation shots. It mainly features Dr Claudia Diaz, Senior Lecturer in Anatomy from the School of Biomedical Sciences speaking to camera. Brightly coloured animations illustrate the various points she makes.

CLAUDIA DIAZ SPEAKS: Whether for strength, or vanity, or a little bit of both – humans are obsessed with sculpting their physiques.

While the general population might use the word “ripped” to describe a muscular person, the scientific term for increasing your muscle size is called “muscular hypertrophy”.

Professional athletes, bodybuilders and yoga instructors have been able to shape their enviable muscles not because their bodies are magical, but because muscles are adaptable.

When we use them a lot, they rise to the challenge – quite literally. When we don’t use them – after an injury for example – they shrink, a process known as muscular atrophy.

But how exactly do our muscles grow?

Let’s start by looking at the different parts of the muscle.

Fascicles are the long, rope-like strands, that make up the muscle. Inside these are the muscle fibers, and inside those, are myofibrils.

When you overuse a muscle, tiny tears are formed in the myofibrils, causing that soreness that many people feel after the gym.

Your immune system steps in to fix the tears, sending proteins called cytokines in to repair the damage you have caused.

Just like sewing up tears in clothing, the cytokines cause the satellite cells surrounding the muscle fiber to multiply in order to repair the the cracks. The new cells fuse with the fiber, regenerating it and increasing the size of the whole muscle in the process.

Diet and genetics can also play a role in how big you get. Protein is the foundation of every muscle, so if you want to look like Arnie, then you’ll need to consume lots of fish, eggs and chicken.

A lot of the repair work that the cytokines do happens when you’re asleep, so make sure you get plenty of rest.

Look after your muscles: They produce movement, help us maintain our posture, support our soft tissue and guard our entrances and exits. They also keep our body temperature nice and even.

As we get older our muscles decrease in size and power, as does our ability to recover from muscular injuries.